VBox Guest Additions fail to install vboxvideo_drv.so module on Linux guests with X v1.19 (which is now delivered with RHEL 7.4). As a result most resolutions as well as auto-resize are unavailable. Problem is also there on 5.1.26

That's true but we don't intend to ship a driver for X.org 1.19 because systems with such a new X server should be able to load the vboxvideo kernel module. Unfortunately RHEL 7 mixes an old kernel (3.10) with a recent X server (1.19). Fortunately RedHat backported relevant DRM code from recent Linux to their custom 3.10.x kernel and we could make the vboxvideo kernel driver work with the RHEL 7.3 and RHEL 7.4 kernels. Please download the most recent Guest Additions from our test builds page. The fix is included in the 5.1 Guest Additions as well as in the most recent 'Development snapshot' Guest Additions. And it will be part of the next Beta as well.

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